For the present, if we can, let us limit our discussion to the Petrine primacy. If, for the sake of argument, we were to stipulate that the theological differences were minor and of non-essential matter, could the Orthodox come into union with Rome while she reiterated the claims made by Leo and other early pope?
As regards papal jurisdictional authority outined in he quote of +Leo the Great, please note that the quote says there arose also a distinction among bishops. Clearly +Leo Great here concedes that the greater authority arose among bishops, leading to different levels of authority, which clearly shows that it was not something given, but evaluational in nature.
I think that you are misrepresenting Leo's position. The distinction that arose among the bishops was "also" among those other than the pope. For he also states:
Even among the most blessed Apostles, though they were alike in honor, there was a certain distinction of power. All were equal in being chosen, but it was given to one to be preeminent over the others.In his letter to the bishops of the province of Vienne in the year 445 he writes:
But the Lord desired that the sacrament of this gift should pertain to all the Apostles in such a way that it might be found principally in the most blessed Peter, the highest of all the Apostles. And He wanted His gifts to flow into the entire body from Peter himself, as if from the head, in such a way that anyone who had dared to separate himself from the solidarity of Peter would realize that he himself was no longer a sharer in the divine mystery.We can see a simular teaching from Pope Gelasius I writing in 495:
Although the universal Catholic Church spread throughout the world has the one marriage of Christ, nevertheless the holy Roman Church has not been preferred to the other churches by reason of synodical decrees, but she has held the primacy by the evangelical voice of the Lord and Savior saying; Thou art Peter, and upon this rock I will build my Church, and the gates of hell shall not prevail against it, and I will give unto thee the keys of the kingdom of heaven, and whatsoever thou shalt bind on earth, it shall be bound also in heaven, and whatsoever thou shalt loose upon earth, it shall be loosed in heaven.We can even see this expressed by the Council of Ephesus in 431:
On one doubts, but rather it has been known to all generations, that the holy and most blessed Peter, chief and head of the Apostles, the pillar of the faith, the foundation stone of the Catholic church, received the keys of the kingdom from our Lord Jesus Christ the Savior and Redeemer of the human race, and that the power of binding and loosing sins was given to him, who up to this moment and always lives in his successors, and judges.
"For the present, if we can, let us limit our discussion to the Petrine primacy. If, for the sake of argument, we were to stipulate that the theological differences were minor and of non-essential matter, could the Orthodox come into union with Rome while she reiterated the claims made by Leo and other early pope?"
In haste as I am at the office; this is precisely what the Orthodox/Roman dialog recently resumed is discussing. The sentiment seems to be that if a working definition of papal primacy can be arrived at which is acceptable all around, the other issues will fall into place. Personally, I think the writings of the Fathers and the Popes from the early years of The Church as well as an in depth study of how whatever primacy The Church actually recognized in the popes worked out "on the ground, then", as opposed to the post hoc, propter hoc reasoning which seems to infest so much of this discussion from both sides, will be vital to any final resolution of this fundamental question. Even that will be difficult because it is not only possible, but likely, that each "side" thought the other understood what it was saying even then, when in fact neither side understood the other after say, the late 500s or early 600s.
We can, with the understanding that no union is possible until it is based on theological unity and not on any agreement on jurisdictional authority of any bishop.
Could the Orthodox come into union with Rome while she reiterated the claims made by Leo and other early pope?
Inasmuch as it is understood that we are dealing with papal opinions and not orders, yes. For +Leo I says "From this formality there arose also a distinction among bishops, and by a great arrangement it was provided that no one should arrogate everything to himself, but in individual provinces there should be individual bishops whose opinion among their brothers should be first"
Even among the most blessed Apostles, though they were alike in honor, there was a certain distinction of power [+Leo I]
I am not sure what he means by "power." If he means ability to do things, I would say, yes because he was given the keys, and only he had possession of them. If it is to mean as being supreme over other bishops, I would say no. Distinction is not supremacy. As the oldest Apostle he received the keys, not because he was better or somehow more faithful than others.
Again, there is no evidence anywhere in the NT that he was given authority to "lord"over other Apostles, not is he ever referred to as the "prince" of the Apostles.
But the Lord desired that the sacrament of this gift should pertain to all the Apostles in such a way that it might be found principally in the most blessed Peter, the highest of all the Apostles [+Leo I].
This is clearly +Leo's personal opinion, not a statement of fact.
"...and that the power of binding and loosing sins was given to [+Peter], who up to this moment and always lives in his successors, and judges..." [Council of Ephesus, 431]
That is rather misleading (if taken out of context), because the power of loosen and bind was given to all the Apostles, not through Peter, but directly by the Lord, although not at the same time, but it was unconditional and independent of +Peter, and that all their successors through them.
That Peter's "supremacy" was not as clear to the Apostles as it is clear to the 21st century Roman Catholic Church is evidenced in the very fact that the Apostles argued who was first among them.
One thing is clear: the office and the power of papal supremacy evolved as is not something the Church taught everywhere and always.